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Fix up parameter passingot match Guy's standards.

    1: #
    2: # $Id: lonlocal.pm,v 1.4 2004/06/01 09:53:44 foxr Exp $
    3: #
    4: # Copyright Michigan State University Board of Trustees
    5: #
    6: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
    7: #
    8: # LON-CAPA is free software; you can redistribute it and/or modify
    9: # it under the terms of the GNU General Public License as published by
   10: # the Free Software Foundation; either version 2 of the License, or
   11: # (at your option) any later version.
   12: #
   13: # LON-CAPA is distributed in the hope that it will be useful,
   14: # but WITHOUT ANY WARRANTY; without even the implied warranty of
   15: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   16: # GNU General Public License for more details.
   17: #
   18: # You should have received a copy of the GNU General Public License
   19: # along with LON-CAPA; if not, write to the Free Software
   20: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   21: #
   22: # /home/httpd/html/adm/gpl.txt
   23: #
   24: # http://www.lon-capa.org/
   25: #
   26: package lonlocal;
   27: 
   28: #
   29: #   Module that provides support for local connections between secure
   30: #   lonc and secure lond.
   31: #
   32: #   A local connection exchanges one-time session keys through a 
   33: #   file that is written in the certificate directory by lonc and
   34: #   read/deleted by lond.  The file is created with permissions
   35: #   rw------- (0600) to prevent it from being snooped unless the system
   36: #   itself has been broken.  In addition the file will not be around
   37: #   for very long so it will be hard to find.
   38: #
   39: 
   40: use strict;
   41: 
   42: # CPAN/standard modules
   43: 
   44: use Crypt::IDEA;
   45: use Fcntl;
   46: 
   47: # LONCAPA modules
   48: 
   49: use LONCAPA::Configuration;
   50: 
   51: # Global variables:
   52: 
   53: my $perlvar;			# Refers to the apache perlsetvar hash.
   54: my $pathsep   = "/";		# Unix path seperator 
   55: my $fileindex = 0;		# Per process lonc uniquifier.
   56: my $lastError;			# Reason for last failure.
   57: 
   58: 
   59: # Initialization
   60: 
   61: $perlvar = LONCAPA::Configuration::read_conf('loncapa.conf');
   62: 
   63: 
   64: #------------------------------------------------------------------------
   65: #
   66: # Name          BuildKey
   67: # Description:  Create an encryption key.
   68: # Returns:      The key.
   69: #
   70: sub CreateCipherKey {
   71: 
   72:     my $keylength;
   73:     my $binaryKey;
   74:     my $cipherkey;
   75:     
   76:     # we'll use the output of /dev/random to produce our key.
   77:     # On a system with decent entropy, this ought to be much more
   78:     # random than all the playing that used to be done to get a key.
   79:     #
   80:     
   81:     $keylength   =  IDEA::keysize();
   82:     open(RANDOM, "</dev/random");
   83:     sysread(RANDOM, $binaryKey, $keylength);
   84:     close RANDOM;
   85:     
   86:     #  The key must be returned in a stringified form in order to be
   87:     #  transmitted to the peer:
   88:     
   89:     my $hexdigits = $keylength*2;	# Assume 8 bits/byte.
   90:     my $template  = "H".$hexdigits;
   91:     $cipherkey = unpack($template, $binaryKey);
   92:     
   93:     return $cipherkey;
   94: }
   95: 
   96: #------------------------------------------------------------------------
   97: #
   98: # Name  	CreateKeyFile
   99: # Description	Creates a private key file and writes an IDEA key into it.  
  100: #
  101: # Returns	
  102: #     A two element list containing:
  103: #     - 	The private key that was  created
  104: #     - 	The full path to the file that contains it.
  105: #     or undef on failure.
  106: sub CreateKeyFile {
  107: 
  108:     # To create the file we need some perlvars to tell us where the
  109:     # certificate directory. We'll make a file named localkey.$pid
  110:     # there, and set the mode before writing into it.
  111:     #
  112:     $fileindex++;
  113:     my $CertificateDir = $perlvar->{lonCertificateDirectory};
  114:     my $Filename       = $CertificateDir.$pathsep.".$fileindex.".$PID;
  115: 
  116:     # If this file already exists, this is a recoverable error... we just
  117:     # delete the earlier incarnation of the file.
  118: 
  119:     if (-w $Filename) {
  120: 	unlink $Filename;
  121:     }
  122: 
  123:     # If the file still exists this is really really bad:
  124:     # It most likely means someone has been devious enough to drop a key file
  125:     # in place to attemp to spoof the lond.  We'll fail in that case hoping
  126:     # that the user looks at the log to figure out that local connections
  127:     # are failing.
  128:     
  129:     if( -e $Filename) {
  130: 	$lastError = "Key file already exists after deletion probably a spoof!";
  131: 	return undef;
  132:     }
  133:     #  Now we can create the file  we use sysopen in order to ensure
  134:     # the file is created with the appropriate locked down permissions.
  135: 
  136:     if(! sysopen(KEYFILE, $Filename, O_CREAT | O_EXCL | O_WRONLY, 0600)) {
  137: 	$lastError = "Creation of key file failed ".$ERRNO;
  138: 	return undef;
  139:     }
  140:     # Create the key, write it to the file and close the file:
  141: 
  142:     my $key = CreateCipherKey();
  143:     print KEYFILE "$key\n";
  144:     close KEYFILE;
  145: 
  146:     return \($key, $Filename);
  147: 
  148:     
  149: }
  150: 
  151: 
  152: # Name  	ReadKeyFile
  153: # Description	Opens the private local key file and reads the IDEA key from it.
  154: # Parameters
  155: #       	Name	          Type	       Description
  156: #               Filename	  string       path to key file
  157: #
  158: # NOTE:
  159: #   Reading the keyfile is a one-time thing.  This sub destroys the
  160: #   keyfile after reading it to ensure the one-timedness of the keys they
  161: #   contain!!
  162: # Returns	
  163: #    On success the IDEA key that was written into the key fileon failure undef.
  164: #
  165: #
  166: sub ReadKeyFile {
  167:     my $Filename = shift;
  168: 
  169:     if(! open(KEYFILE, "<$Filename")) {
  170: 	$lastError = "Key file open failed";
  171: 	return undef
  172:     }
  173:     my $key = <KEYFILE>;
  174:     chomp;
  175:     close KEYFILE;
  176:     unlink $Filename;
  177:     #
  178:     #  If the filename still exists some spoofer wrote it with the wrong
  179:     #  permissions:
  180:     #
  181:     if(-e $Filename) {
  182: 	$lastError = "Key file still exists after unlink";
  183: 	return undef;
  184:     }
  185:     #
  186:     #  The IDEA key must be  IDEA::keysize*2 characters
  187:     #  long.   If it  isn't probably someone's trying to break us by
  188:     #  hitting the timing hole between the file write and read...
  189:     #  replacing our file... of course if they read this comment they'll
  190:     #  be too smart to put an incorrectly sized file
  191:     #
  192:     if(length($key) != IDEA::keysize*2) {
  193: 	$lastError = "Key file has incorrect length";
  194: 	return undef;
  195:     }
  196:     return $key;   
  197: }